The present invention relates to the field of personal safety systems and in particular to a system for indicating when a crewman, child or other person in a waterside environment accidentally enters the water. There are many instances when young children, playing near the water, cannot be continuously observed by adults or when adult attention is diverted for a period of time often sufficient to permit the child to accidentally fall into the water. A serious accident may result if the attending adult is not immediately summoned. The crew of many ships are also exposed to the risk of accidentally falling into the water while unobserved. This is particularly true of fishing vessels where crew activity takes place around the railing, hauling and setting fishing gear. On any vessel at night there exists an increased danger to crewmen from falling overboard due to the higher chance that the accident will go unobserved.
Systems exist for detecting a "man overboard" situation and operate by, for example, receiving an ultra-sound signal transmitted through the water upon submergence of a transmitting unit which is worn about the body of an individual to be protected and activated by immersion of the individual. Such systems depend for their reliability on the activation of the transmitter upon immersion of the individual. In situations involving strenuous physical work by crewmen or the intervention of curious children, the possibility of a failure to activate the transmitting mechanism exists. The results of such a failure, particularly where the security system is relied upon to the exclusion of traditional safety measures, could be tragic.